In recording instruments, it is often desirable to provide a pivotal connection between the marker (or pen, for present purposes the terms "marker" and "pen" are used interchangeably) support arm and an operating shaft of the marker with respect to a chart or the like which is to be imprinted upon by the marker.
In U.S. Pat. No. 3,771,166 (Tullos), lateral positioning of the marker is controlled by a micrometer screw which is threaded through a port that is carried by an arm which is rigidly connected to the operating arm of the recorder. Engagement of the micrometer screw actuates pivotal movement of the marker support arm about a fulcrum pin which connects the marker support arm to the arm which is to be rigidly connected to the recorder operating arm. U.S. Pat. No. 3,264,652 (Squier) discloses a similar mechanism.
In U.S. Pat. No. 3,311,920 (Thompson), positioning of the marker is controlled by the provision of a hub which connects the marker support arm to a rotatable drive shaft.
In U.S. Pat. No. 2,646,337 (Gorham), the operating shafts 128 of the instrument are connected to the writing instruments 12 and their associated spindles 124 by the provision of crank arms 130 to actuate oscillating movement of the writing instruments (see FIG. 2 of this reference patent).
Another means for adjustably positioning the writing elements in relation to a recorder chart is shown in U.S. Pat. No. 3,383,702 (Donahue) wherein the writing instruments are carried in pivotal balls which are adjustably positioned in "U" shaped brackets that are rigidly bolted to the instrument frame.
Despite these prior art mechanisms, there remains a need in the art for an assembly that provides reliable pivotal positioning of the marker relative to the operating shaft of the recorder instrument so that the marker may be adjustably, laterally positioned with respect to the desired recorder paper or chart which is to be imprinted thereon.
There also remains a need for such an assembly which securely holds the marker in its desired, adjusted position even when vibrational stress is exerted on the marker support arm.
Further, there remains a need for a marker instrument mounting assembly providing pivotal movement of the marker relative to the instrument operating arm that it is readily manually actuated by the instrument operator. Moreover, an assembly that also provides a means for gauging the relative positions of the pen and operating arm is especially desirable.
These and other needs are met by the recording instrument marker mounting assembly and precision adjustment control knob disclosed herein, which will be understood more clearly and fully from the following detailed description, when read in conjunction with the accompanying drawings.